We propose 1) to continue our investigation of the etiology and mechanism of cataractogenesis in animal model systems, and 2) to apply our positive findings to the study of human cataracts. The present research concerning the biochemical and biophysical characteristics of lens proteins and their changes in the process of lens opacification has been progressing on schedule. The rat lens protein has been separated into alpha, beta, gamma crystallins F-II and F-VI fractions by gel chromatography in this laboratory. The chemical structure of F-II protein and its probable involvement in cataractogenesis has been under our investigation. Whether the F-II protein in rat lens is analogous to the beta H protein described in other mammalian lenses is also an important topic. The sequential changes of protein in neonatal rat lens has yielded information on the biosynthetic pattern of rat lens protein. Experiments to demonstrate the systematic destruction of lens fibers, by galactose induction, in the neonatal rat have been conducted. For human lens, it is planned to complete the mapping of the distribution and molecular weights of both normal and cataractous lenses. The isolation and characterization of the F-II protein of human lens is in progress.